By immunohistochemistry, we detected expression of all four PGE2 receptor subtypes, EP1, EP2, EP3 and EP4, in the tumor cells of all primary neuroblastomas investigated, independent of any biological characteristics or clinical stage (Figures 1A and B).The receptors were also expressed in the vasculature of the adjacent stromal tissue. The gene discussed is PTGER4; the disease is neuroblastoma.